This proposal presents new approaches for studying the brain basis of vocal communication. Songbirds learn their vocalizations from external tutors through a process of imitation that resembles human speech acquisition. These learned vocalizations are used to communicate with conspecifics in social and reproductive contexts. Previous work has defined a specialized brain circuit for vocal learning and production that enables these processes to be studied at the neural level. I propose to explore the sensory and motor representations of this learned skill by studying the production and sensory processing of vocal signals in the brains of zebra finches. The projects described will focus on two structures in the telencephalon: one is on the final vocal motor pathway, and the other is an auditory integration area. These projects will use neurophysiological, neuroanatomical, and behavioral methods. Specifically, I propose to study l) The generation of the motor pattern that underlies the temporal structure of learned vocalizations; 2) The auditory representation of learned song in both the sensory and motor pathways; 3) Vocal response behavior in order to assess perceptual discrimination and auditory learning; 4) The development of auditory responses and neural activity patterns in the brains of young birds during song learning. The songbird vocal control system provides an exciting opportunity to relate the phenomena of a naturally learned behavior to its neural substrate, and ultimately its cellular basis.